(a) Technical Field
The present disclosure relates generally to an anti-jerk control apparatus and method for a Hybrid Electric Vehicle (HEV). More particularly, the present invention relates to an anti-jerk control apparatus and method for an HEV, which can prevent vibrations from occurring on a drive shaft at the time of changing gears and performing a tip-in/out, as well as at the time of releasing the clutch, by using the torque control of a motor.
(b) Background Art
A Hybrid Electric Vehicle (HEV) employs a motor driving source as an auxiliary power source, in addition to an engine, and thus can reduce waste gas and improve fuel economy. The construction of a driving system (power train system) for a parallel HEV is described below. As shown in the block diagram of FIG. 4, the power train system is configured such that an engine 10, a motor 20 and an automatic transmission 30 are suitably disposed in a collinear fashion on a drive shaft 90, and such that a clutch 40 is suitably disposed between the engine 10 and the motor 20. Further, as components for operating the above components, a Hybrid Starter Generator (HSG) 70 is suitably connected to the crank pulley of the engine by a belt, and a high-voltage battery 50 is chargeably or dischargeably connected both to the motor 20 and to the HSG 70 through an inverter 60.
Further, a scheme using a Transmission Mounted Electric Device (TMED) in which an electric motor is assembled to an automatic transmission has been used.
The driving modes of a hybrid electric vehicle based on the above construction include an Electric Vehicle (EV) mode, that is, a pure electric vehicle mode in which only the power of a motor is used, an HEV mode in which the motor is used as an auxiliary power source while the engine is used as a main power source, and a Regenerative Braking (RB) mode in which the motor recovers braking and inertial energy of a vehicle by the generation of power and recharges the battery with the energy while the vehicle is braking, or being driven under inertia.
In such an HEV, since the engine is suitably coupled to the automatic transmission using a clutch instead of a torque converter, there is a disadvantage in that the passive damping effect of a conventional torque converter cannot be suitably obtained.
Since a separate damping means is excluded in this way, vibrations such as shock and jerk (instantaneous, sudden movement), together with the vibration of a drive shaft, occur at the time of changing gears, performing a tip-in/out (operation of pressing or releasing an accelerator pedal), and engaging the clutch, thus deteriorating riding comfort and drivability.
Further, both the automatic transmission 30, suitably disposed between the motor 20 and a driving wheel 80, and a final reduction gear (not shown), connected to the output shaft of the automatic transmission 30, have gear elements having backlash characteristics, but they lack damping elements such as torsional dampers. Accordingly, when the direction of effective transfer torque is changed, a vibration attributable to backlash occurs.
Therefore, in an effort to damp such a vibration, various methods, such as a passive damping method, a closed-loop controlled active damping method and an open-loop controlled torque profiling method, have been used. The passive damping method is a method of additionally and separately mounting a physical damping element such as a physical torsional damper. The closed-loop controlled active damping method is a method of enabling a damping force to be actuated in the reverse direction of vibration. The open-loop controlled torque profiling method is a method of canceling exciting components on the basis of a vibration mechanism.
However, in the passive damping method, a physical damper must be additionally mounted on a driving system, and it is difficult to cope with the problem of packaging and design caused by the addition of the damper. Further, the active damping method requires the design of a high-performance sensor and a high-performance observer. Furthermore, in the torque profiling method, various types of torque modifications are taken into consideration, and thus it is difficult to obtain complete vibration damping performance.
In order to prevent a vibration (jerk) from occurring during the engagement of the clutch between the engine and the automatic transmission, anti-jerk control for increasing engine torque has been performed by an engine controller (Engine Management System: EMS). However, since the engine is disconnected from the drive shaft when the clutch is released, the anti-jerk control cannot be performed, thus making it impossible to suppress jerk components caused by the release of the clutch.
Japanese Patent Laid-Open Publication No. 2002-262408, incorporated by reference in its entirety herein, discloses a technology in which torque correction values are set based on an inertial relationship between an engine and a motor, and in which, when a difference in the rotation speed between the engine and the motor occurs, the torque of the motor is suitably corrected by using a predetermined torque correction value corresponding to the difference in the rotation speed. Further, Korean Patent Publication No. 2009-62871, incorporated by reference in its entirety herein, discloses a technology in which, when a clutch release command is given, driving control is suitably performed in an EV mode, thus preventing a shock phenomenon. However, even if the above technologies are applied, forward torque (+) is input by the engine, and thus a jerk phenomenon attributable to the engagement/release of the clutch cannot be fundamentally blocked.
Accordingly, there remains a need in the art for an anti-jerk control apparatus and method for an HEV.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.